1. Field of the Invention
The present invention relates to a semiconductor device.
2. Description of the Related Art
An electronic device mounts various semiconductor devices having various kinds of functions, examples of which include a power supply circuit, a motor driver, an LED (Light Emitting Diode), a DSP (Digital Signal Processor).
In some cases, a designer or a manufacturer of electronic devices (who will be referred to as the “set maker” hereafter) desires to switch the operation mode or the function of the semiconductor device as desired from outside the semiconductor device. In order to fulfill such a request, a designer or a manufacturer of semiconductor devices (who will be referred to as the “device supplier” hereafter) provides several control pins to a semiconductor device, which allows the set maker to set the operation mode and the function of the semiconductor device from outside the semiconductor device.
FIG. 1 is a diagram which shows an example configuration of a typical semiconductor device. A semiconductor device 200 includes a semiconductor chip 202, a substrate 204, and multiple pins PIN. The semiconductor chip 202 includes multiple pads PAD1 through PAD5. For example, the pad PAD1 functions as a power supply pad via which a power supply voltage Vdd is supplied. The third pad PAD3 functions as an input pad via which an input signal to be processed is received. The fourth pad PAD4 functions as an output pad via which the processed signal is output. The semiconductor chip 202 is configured so as to allow the state and the function (which will be collectively referred to as the “state” hereafter) to be switched according to the values of control signals input to the first pad PAD1 and the second pad PAD2. In a case in which each of the two control signals can be set to one of two levels, i.e., a high level or a low level, such an arrangement allows the semiconductor chip 202 to switch the state between a maximum of four states.
The semiconductor chip 202 is mounted on the substrate 204. Multiple pins PIN that correspond to the multiple pads PAD are fixed to the substrate 204. The pins PIN and the corresponding pads PAD are electrically connected by means of connection members such as bonding wires or the like. With such an arrangement, the semiconductor chip 202 can be set to a desired state by supplying the control signals, each of which can be set to high level or low level, to the control pins PIN1 and PIN2 connected to the first pad PAD1 and the second pad PAD2.
Such an arrangement has a problem in that an increase in the number of control signals leads to an increase in the number of pins PIN. Such an increase in the number of pins PIN leads to an increased package size, consequently limiting the size of the electronic device. Furthermore, this leads to an increase in the cost of the semiconductor device.